Military Sweater with patches for a band

[The Wizard of BC]

I guess you can put me in the KISS group too. Keep it Simple Stupid.

Rank? Do you need to show a rank? Are you in the military? If so follow your uniform regulations.
Flag? Do you need to display a flag? Are you performing in a foreign country where there may be some doubt where you are from? Are their members of the band from various nations that you need to show what nation each is from?
Band Patch? Does every member need to display a band patch? If I want to know what band I am seeing I will look at the banner out front or on the bass drum. And I doubt I could see, or read, a band patch on the left breast under the pipes anyway.

Have you ever seen rank, flag and band patch on a band dressed in Argyle Jackets?

There is no right/wrong, proper/improper. There is only the agreed upon band uniform. Whatever that is. Ultimately it comes down to what your Drum or Pipe Major wants. Some bands dress in a plain shirt and tie. Some in full doublets. And everything in between. In fact I have usually found that each band wants to be different and distinctive from the other bands. If each band is dressed differently who is it up to, to decide which is the "proper" one?